Steering column adjusting device and steering column adjusting method

The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2024-134328 filed on Aug. 9, 2024. The content of the application is incorporated herein by reference in its entirety.

The present invention relates to a steering column adjusting device and a steering column adjusting method.

In recent years, efforts to provide access to sustainable transportation systems that take into consideration vulnerable persons among traffic participants have become active. In order to achieve this, attention has been focused on research and development to further improve traffic safety and convenience through research and development related to driving assistance techniques.

Japanese Patent Laid-Open No. 2006-96206 discloses a driving posture adjusting device that finely adjusts a driving position of a target part of a vehicle, such as a seat or a steering wheel, when it is detected that a driver is dissatisfied with the driving position of the target part.

Incidentally, the driving assistance technique has a problem to accurately adjust a posture of a steering column, which is a part of a steering device, to a posture preferred by the driver.

In the above-described related art, when there is a deviation in a position detection of the target part in a case of finely adjusting the driving position of the target part, it may not be possible to adjust the driving position of the target part with high accuracy enough to alleviate dissatisfaction of the driver.

In order to solve the above problems, the present application aims to appropriately modify a deviation in detection of a posture of a steering column and to enable adjustment of the posture of the steering column with high accuracy. Thus, the present application contributes to development of a sustainable transportation system.

A first aspect of the present invention provides a steering column adjusting device that adjusts a posture of a steering column of a vehicle, the steering column adjusting device including: an actuator that drives a posture adjusting mechanism of the steering column to move a posture position of the steering column within a movable range defined by two movable limit positions in the posture adjusting mechanism; and a detection unit that detects a current posture position of the steering column, the detection unit being configured to detect the current posture position of the steering column from an operating value indicating an operation amount of the actuator based on one of the movable limit positions, the detection unit being configured to store the operating value indicating an overload position, which is the posture position at which the actuator is put in an overload equal to or greater than a predetermined threshold during an operation of the actuator, the detection unit being configured to modify, when the operating value indicating a current overload position detected when the actuator is operated in one moving direction matches, within a predetermined error range, with the operating value indicating a previous overload position stored in a previous operation of the actuator in the one moving direction, the operating value such that the current overload position is the movable limit position in the one moving direction.

A second aspect of the present invention provides a steering column adjusting method executed by a computer of a steering column adjusting device that adjusts a posture of a steering column of a vehicle, the steering column adjusting method including: a setting step of driving a posture adjusting mechanism of the steering column using an actuator to move a posture position of the steering column within a movable range defined by two movable limit positions in the posture adjusting mechanism; and a detection step of detecting a current posture position of the steering column, the detection step including detecting the current posture position of the steering column from an operating value indicating an operation amount of the actuator based on one of the movable limit positions, storing the operating value indicating an overload position, which is the posture position at which the actuator is put in an overload equal to or greater than a predetermined threshold during an operation of the actuator, modifying, when the operating value indicating a current overload position detected when the actuator is operated in one moving direction matches, within a predetermined error range, with the operating value indicating a previous overload position stored in a previous operation of the actuator in the one moving direction, the operating value such that the current overload position is the movable limit position in the one moving direction.

According to aspects of the present invention, it is possible to appropriately modify a deviation in detection of a posture of a steering column and to enable adjustment of the posture of the steering column with high accuracy.

An embodiment of the present invention will be described below with reference to the drawings.

is a diagram illustrating an example of a configuration of an electric steering columnof a vehicleto which a steering column adjusting deviceaccording to an embodiment of the present invention is applied. The vehicleis, for example, an electric vehicle driven by a battery. The electric steering columnincludes, as posture adjusting mechanisms for a steering column, a tilt steering mechanismthat adjust a tilt angle θ (to be described below) which is an angle in an elevation angle direction EL of the steering column, and a telescopic steering mechanismthat adjusts a front-back position P(to be described below) which is a position in a front-back direction FB of the steering column. Hereinafter, unless otherwise distinguished, the tilt steering mechanismand the telescopic steering mechanismwill be collectively referred to as a posture adjusting mechanism.

The tilt steering mechanismand the telescopic steering mechanismare driven by actuatorsand, respectively. Hereinafter, unless otherwise distinguished, the actuatorsandwill be collectively referred to as an actuator.

The actuatordrives the posture adjusting mechanismof the steering columnto move a posture position of the steering columnwithin a movable range defined by two movable limit positions in the posture adjusting mechanism.

Specifically, the actuatordrives the tilt steering mechanismto change the tilt angle θ of the steering columnwithin a movable range LRdefined by two movable limit positions Aand Ain the tilt steering mechanism, thereby moving a posture position in an elevation angle direction EL of the steering column. Here, the tilt angle θ can be defined as, for example, an angle measured from the movable limit position Ain a direction toward the movable limit position A, with the movable limit position Abeing set as a zero (0) degree. The tilt angle θ has a maximum value θat the movable limit position A

In addition, the actuatordrives the telescopic steering mechanismto change a front-back position Pof the steering columnwithin a movable range LRdefined by two mechanical movable limit positions Pand Pin the telescopic steering mechanism, thereby moving a posture position in the front-back direction FB of the steering column. Here, the front-back position Pcan be defined as, for example, a distance measured from the position of the movable limit position Pin a direction of the movable limit position P. The front-back position Phas a maximum value Pat the movable limit position P.

Hereinafter, unless otherwise distinguished, the movable limit positions Aand Pwill be collectively referred to as a movable limit position LU, and unless otherwise distinguished, the movable limit positions Aand Pwill be collectively referred to as a movable limit position LL. Unless otherwise distinguished, the movable ranges LRand LRwill be collectively referred to as a movable range LR.

In other words, the actuatordrives the posture adjusting mechanismof the steering columnto move the posture position of the steering columnwithin the movable range LR defined by two movable limit positions LU and LL in the posture adjusting mechanism.

In the following description, regarding operations common to the tilt steering mechanismand the telescopic steering mechanismwill be described as operations of the posture adjusting mechanism, which is a general term for the tilt steering mechanismand the telescopic steering mechanism. Hereinafter, the operation of the posture adjusting mechanismcommon to the tilt steering mechanismand the telescopic steering mechanismmay be specifically described using the operation of the tilt steering mechanismand/or the telescopic steering mechanism

The steering column adjusting deviceadjusts the posture of the steering columnby operating the actuatorof the posture adjusting mechanismin response to an input from a column adjusting switchactuated by a driver of the vehicleand/or a change in state of a vehicle power switchwhich turns on and off a power supply (not illustrated) of the vehicle. Here, the steering column adjusting deviceacquires information indicating a state of the vehicle power switchwhen the vehicle power switchis actuated via, for example, a vehicle control devicethat is mounted in the vehicleand that includes a second processor to control the vehicle, and thus detects a change in state of the vehicle power switch. In addition, when the vehicleis driven by an internal combustion engine, the vehicle power switchmay be an ignition switch that starts or stops the operation of the internal combustion engine. The steering column adjusting deviceand the vehicle control deviceare communicably connected to each other via an in-vehicle network bus.

The column adjusting switchmay be disposed on a steering wheelor an instrument panel (not illustrated) of the vehicle. The column adjusting switchis, for example, a rocker switch, and instructs the steering column adjusting deviceto move the posture position in the elevation angle direction EL upward or downward when an arrow pointing upward or downward illustrated in the drawing is pressed. In addition, the column adjusting switchinstructs the steering column adjusting deviceto move the posture position in the front-back direction FB forward or backward when an arrow pointing leftward or rightward illustrated in the drawing is pressed.

The actuatorsandinclude sensorsandthat generates a predetermined signal for each unit operation amount of the actuatorsand, respectively. Hereinafter, unless otherwise distinguished, the sensorsandwill be collectively referred to as a sensor.

In the present embodiment, as an example, each of the actuatoris a stepping motor.is a diagram illustrating an example of a cross-sectional configuration orthogonal to a rotation axis of the stepping motor, which is the actuator. The actuator, which is the stepping motor, includes a magnet rotor, a stator, and one sensorthat is a Hall sensor. The magnet rotoris a cylindrical magnet having a plurality of magnetic poles arranged at equal intervals along a circumference, and rotates together with the rotation axis. In the configuration illustrated in, the magnet rotorhas two magnetic poles, as an example. In other words, the magnet rotorhas one S pole and one N pole arranged respectively in half-circumference regions that divide an outer circumference of the magnet rotorinto two equal parts. The number of magnetic poles can be any multiple of two, depending on the design of the stepping motor according to the related arts.

The statoris formed of a cylindrical magnetic body including a plurality of coils arranged at equal intervals along an inner circumference. In the configuration of, as an example, the statorincludes four coils. The four coils are energized by a drive control circuit. In addition, the shape of the statorand the number of coils can be any number other than four depending on the design of the stepping motor according to the related arts.

The drive control circuitis arranged on the posture adjusting mechanism. The drive control circuitsequentially changes the magnetic poles generated in the four coils to a clockwise direction or a counterclockwise direction according to the related arts to rotate the magnet rotorin a clockwise direction or a counterclockwise direction. Specifically, the drive control circuitrotates the magnet rotorin a clockwise direction or a counterclockwise direction, or stops rotating, according to a voltage value of an instruction voltage Vapplied from the steering column adjusting device.

The sensoris arranged near the outer circumference of the magnet rotor, for example. The sensormay include not only a Hall element but also an integrated circuit for outputting the output of the Hall element as a voltage output.

According to a known technique, the sensoroutputs a square wave signal Sas a voltage signal according to a change in magnetic field applied to the sensor, as the magnetic poles of the magnet rotorpass through the position of the sensoras the magnet rotorrotates. Since the magnetic poles are arranged at equal intervals in the magnet rotor, the square wave signal Sbecomes a High level with each rotation of a unit angle corresponding to the intervals between the magnetic poles as the magnet rotorrotates.

In the present embodiment, the square wave signal Soutput from the sensorbecomes, for example, a High level while an N pole of the magnet rotorpasses the position of the sensor, and becomes a Low level while an S pole passes. In the configuration of, since the magnet rotorhas an S pole and an N pole arranged respectively in half-circumference regions that divide an outer circumference thereof into two equal parts, the N pole passes the position of the sensorevery time the magnet rotorrotates once. Therefore, in the present embodiment, the unit angle is 360 degrees. In other words, the square wave signal Soutput from the sensorincludes a pulse signal Sp that becomes a High level every time the magnet rotorrotates through a 360-degree unit angle. The sensoroutputs the square wave signal Sto the steering column adjusting device.

In the present embodiment, the brushless stepping motor including the magnet rotorhas been illustrated as an example of the actuator, but the actuatormay be a brush-equipped stepping motor including a rotor coil. In the case of the brush-equipped stepping motor, the sensoras a Hall sensor may be provided near the rotor coil. Thus, similarly to the above-described brushless stepping motor, the sensorcan output a square wave signal Sincluding a pulse signal Sp generated each time the rotor coil rotates at a predetermined unit angel.

is a graph illustrating an example of the square wave signal Soutput from the sensorto the steering column adjusting device. In, a vertical axis represents a voltage value V, and a horizontal axis represents time t.illustrates a change in the square wave signal Sover time when the magnet rotorrotates at a constant speed. As illustrated in the drawing, the square wave signal Salternates between a voltage VH of a High level and a voltage VL of a Low level as the N pole and the S pole of the magnet rotorsequentially pass through the position of the sensor, which is a Hall sensor. As a result, as described above, the square wave signal Sincludes the pulse signal Sp generated each time the magnet rotorrotates at a unit angle of 360 degrees.

The steering column adjusting devicedetects the current posture position of the steering column, from an operating value that indicates the operation amount of the actuatorbased on one movable limit position of the posture adjusting mechanism, for example, the movable limit position LL. The operating value is a count value obtained by adding and subtracting the number of times of generating a predetermined signal for each unit operation amount of the actuatoraccording to the operation direction of the actuator. The operating value may represent the operation amount of the actuatorbased on the movable limit position LU.

In the present embodiment, the predetermined signal is the pulse signal Sp included in the square wave signal Soutput from the sensor, which is generated every time the magnet rotorof the stepping motor serving as the actuatorrotates at a unit angle.

The steering column adjusting devicecan grasp the rotation angle of the magnet rotor, that is, the operation amount of the actuatorserving as the stepping motor, from a count value Nc obtained by adding and subtracting the number of times of generating the pulse signal Sp according to the rotation direction of the magnet rotor. The steering column adjusting devicedetects the current posture position of the steering columnfrom the count value Nc, which is an operation value indicating the operation amount of the actuatorserving as a stepping motor.

Specifically, the steering column adjusting devicesets the count value Nc to 0 (zero) when the steering columnis at one movable limit position LL of the posture adjusting mechanism. Then, the steering column adjusting deviceadds the number of times of generating the pulse signal Sp, which is output from the sensor, to the count value Nc when the steering columnrotates the magnet rotorto move toward the other movable limit position LU of the posture adjusting mechanism. In addition, the subtracts the number of times of generating the pulse signal Sp, which is output from the sensor, to the count value Nc when the steering columnrotates the magnet rotorto move toward the one movable limit position LL of the posture adjusting mechanism.

Thus, the count value Nc represents the operation amount of the actuatorbased on the one movable limit position LL of the posture adjusting mechanism, and indirectly represents the current posture position of the steering columnthat moves between the one movable limit position LL and the other movable limit position LU.

Hereinafter, the count value Nc regarding the number of times of generating the pulse signal Sp from the sensorof the tilt steering mechanismis referred to as a count value Nc, and the count value Nc regarding the number of times of generating the pulse signal Sp from the sensorof the telescopic steering mechanismis referred to as a count value Nc. In other words, the count value Ncrepresents the posture position of the steering columnthat moves from the one movable limit position Aof the tilt steering mechanismtoward the other movable limit position A. In addition, the count value Ncrepresents the posture position of the steering columnthat moves from the one movable limit position Pof the telescopic steering mechanismtoward the other movable limit position P.

Hereinafter, unless otherwise distinguished, the count value Ncand the count value Ncwill be collectively referred to as a count value Nc.

In the following description, the operation direction of the actuator, in which the posture position of the steering columnis directed toward the movable limit position LU from the movable limit position LL, is referred to as a “forward direction”, while the operation direction of the actuator, in which the posture position of the steering columnis directed toward the movable limit position LL from the movable limit position LU, is referred to as a “reverse direction”. In addition, the rotation direction of the magnet rotorcorresponding to the operation in the forward direction of the actuatorserving as a stepping motor is referred to as a “forward rotation direction”, while the rotation direction of the magnet rotorcorresponding to the operation in the reverse direction of the actuatoris referred to as a “reverse rotation direction”.

The magnet rotorrotates in the forward rotation direction when the steering column adjusting deviceinputs a forward rotation instruction voltage V, which is a positive voltage, as an instruction voltage Vto the drive control circuitof the actuatorserving as a stepping motor, and rotates when the steering column adjusting deviceinputs a reverse rotation instruction voltage Vwhich is a negative.

is a graph illustrating an example of a change in count value Ncover time with respect to the pulse signal Sp output from the sensorprovided in the actuatorthat drives the tilt steering mechanism

An upper stage inindicates a graph illustrating a change over time of the instruction voltage Voutput by the steering column adjusting deviceto the drive control circuitof the actuatorwhich is a stepping motor. In the upper stage in, a vertical axis represents voltage, and a horizontal axis represents time. Further, a lower stage inindicates a graph illustrating an example of a change over time of the count value Ncaccording to the change over time of the instruction voltage Villustrated in. In the lower stage in, a right vertical axis of two vertical axes represents the count value Nc, and a vertical axis on a left side of the count axis represents a tilt angle θ, which is a posture position in the elevation angle direction EL of the steering columncorresponding to the count value Nc. Here, the vertical axis representing the count value Ncon the right side is referred to as a count axis, and the vertical axis representing the tilt angle θ on the left side is referred to as a tilt axis.

In the example illustrated in, as illustrated by the tilt axis and the count axis in the lower stage in, the position of the movable limit position Aof the tilt steering mechanism, that is, the posture position of the steering columnhaving a tilt angle θ (=0) corresponds to [count value Nc=0], and the position of the movable limit position Aof the tilt steering mechanism, that is, the posture position of the steering columnhaving a tilt angle θ (=θ) corresponds to, for example, [count value Nc=400]. Further, a method of determining the count value Nc corresponding to the posture position of the steering columnhaving the tilt angle θ (=θ) will be described below with reference to. The above-described [count value Nc=400] is an example of a correct count value Nc(Nclimit value Vto be described below) corresponding to the movable limit position A.

A range between the movable limit position Aindicated by the tilt angle θ (=0) on the tilt axis and the movable limit position Aindicated by the tilt angle θ (=θ) corresponds to the movable range LR.

The steering column adjusting deviceadjusts the posture of the steering columnwithin a set allowable range SRnarrower than the movable range LRto avoid the actuatorfrom colliding with the movable limit position Aand/or movable limit position Adue to a count error in the count value Nc. The set allowable range SRis defined as a range between two set limit positions Aand A, which are distant from the two movable limit positions Aand Aby a predetermined margin range, respectively. In the example of the lower stage in, the set allowable range SRis defined as a range that provides a margin range of 20 counts in the count value Ncfrom the movable limit positions Aand A, and the set limit positions Aand Acorrespond to the count values Ncof 20 and 380, respectively.

As described above, the steering column adjusting deviceadjusts the posture of the steering columnwithin a set allowable range SRnarrower than a movable range LRto avoid the actuatorfrom colliding with the movable limit position Pand/or movable limit position Pdue to a count error in the count value Ncwith respect to the telescopic steering mechanism. The set allowable range SRis defined as a range between two set limit positions Pand P, which are distant from the two movable limit positions Pand Pby a predetermined margin range, respectively.

Hereinafter, unless otherwise distinguished, the set limit positions Aand Pwill be collectively referred to as a set limit position SL, and unless otherwise distinguished, the set limit positions Aand Pwill be collectively referred to as a set limit position SU. Furthermore, unless otherwise distinguished, the set allowable range SRand the set allowable range SRwill be collectively referred to as a set allowable range SR.

In other words, the steering column adjusting deviceadjusts the posture of the steering columnwithin the set allowable range SR narrower than the movable range LR of the posture adjusting mechanism. The set allowable range SR is defined as a range between two set limit positions SL and SU, which are distant from two movable limit positions LL and LU by a predetermined margin range, respectively.

Referring to, first, at time t, for example, when an instruction is given from the column adjusting switchto move the steering columnupward in the elevation angle direction EL, the steering column adjusting devicesets the instruction voltage Vto a forward rotation instruction voltage Vin order to move the actuatorin the forward direction, and rotates the magnet rotorof the actuatorin the forward rotation direction. While moving the actuatorin the forward direction, the steering column adjusting deviceadds 1 to the count value Ncevery time the pulse signal Sp is output from the sensorof the actuator. Thus, the count value Ncincreases with time, and reaches a value of 380, which corresponds to the set limit position Aof the set allowable range SR, at time t. When the count value Ncreaches the value of 380 corresponding to the set limit position A, the steering column adjusting devicesets the instruction voltage Vto 0 (zero) V and stops the operation of the actuator. Thus, the steering columnis held in the posture position of the tilt angle corresponding to the set limit position A.

Then, at time t, when an instruction is given from the column adjusting switchto move the steering columndownward in the elevation angle direction EL, the steering column adjusting devicesets the instruction voltage Vto the reverses rotation instruction voltage Vin order to move the actuatorin the reverse direction, and rotates the magnet rotorof the actuatorin the reverses rotation direction. While moving the actuatorin the reverse direction, the steering column adjusting devicesubtracts 1 from the count value Ncevery time the pulse signal Sp is output from the sensorof the actuator. Thus, the count value Ncdecreases with time.

At time t, when the count value Ncreaches a value of 20 which corresponds to the set limit position Aof the set allowable range SR, the steering column adjusting devicesets the instruction voltage Vto 0 (zero) V, and stops the operation of the actuator. Thus, the steering columnis held in the posture position of the tilt angle corresponding to the set limit position A.